Abstract: The object of the present invention is to provide a method of producing low oxygen-containing potassium fluorotantalate crystals or low oxygen-containing potassium fluoroniobate crystals, the crystals obtained by the production method, and a method of analyzing oxygen contained in these crystals. The method of producing low oxygen-containing potassium fluorotantalate crystals comprises generating recrystallized potassium fluorotantalate crystals by controlled cooling of a saturated solution of potassium fluorotantalate containing hydrofluoric acid as an essential component, collecting the generated recrystallized crystals through filtration, and drying the collected recrystallized crystals in a drying apparatus so as to obtain the crystals, and the production method is characterized in that the saturated solution of potassium fluorotantalate containing hydrofluoric acid as an essential component contains hydrofluoric acid in a concentration of 0.5 mol/l to 10 mol/l.

Abstract: This invention aims to provide a method of manufacturing a cerium-based abrasive containing coarse particles in lower concentration and having higher polishing ability and excellent cleanability for a polished face. Further, the present invention provides a method of manufacturing a cerium-based abrasive, including the steps of pulverizing a raw material, roasting a raw material after pulverization and disintegrating a raw material after roasting, in which a cerium-based rare earth carbonate or a mixture of a cerium-based rare earth carbonate and a cerium-based rare earth oxide is used as a cerium-based abrasive raw material, and the step of pulverizing a raw material pulverizes a raw material through heating while the material is kept immersed in aqueous solution.

Abstract: This invention is a method for producing a cerium-based abrasive which includes: a step of grinding raw material for the cerium-based abrasive; a step of roasting the ground raw material; and a step of subjecting the roasted raw material to wet processing, the method being characterized in that it further includes a lower-temperature re-roasting step of heating the wet-processed raw material at 200 to 700° C. In the invention disclosed in this application, an abrasive with particularly preferable properties can be produced by fully drying the wet-processed raw material in a drying step, and subsequently subjecting the dried raw material to the lower-temperature re-roasting step.

Abstract: The present invention provides a cerium-based abrasive slurry particles including a cerium-based abrasive particle of no less than 95% by weight of total rare earth oxides (TREO), in which the cerium-based abrasive particle has less than 3% by weight of fluorine content of TREO, and a particle size distribution determined by a laser diffraction method is within a predetermined range. And adhesion property is further improved by setting this fluorine content in 0.005 to 0.5% by weight of TREO.

Abstract: A cerium-based abrasive and a production method of the cerium-based abrasive excellent in polishing properties of a high polishing speed and scarce formation of polishing scratches are provided by keeping the color of the abrasive in specified ranges or stably making fluorine be contained in the abrasive. For example, as such a cerium-based abrasive, examples include a cerium-based abrasive containing cerium oxide as a main component and having an L* value in a range not lower than 65 and or lower 90, an a* value in a range 0 or higher but 15 or lower, and a b* value in a range 10 or higher but 30 or lower in the case the color is expressed by an L*a*b* color system.

Abstract: A polishing material is provided in which the dispersibility of the abrasive grains of the polishing material having, as a major component, rare earth oxides including cerium oxide is made better and the hardness of abrasive grain precipitates is reduced, and at the same time high efficiency of polishing can be achieved stably. According to the present invention, in a polishing material having, as the major component, rare earth oxides including cerium oxide, any one of crystalline cellulose, calcium secondary phosphate, a condensate of sodium &bgr;-naphthalenesulphonate and formalin, and synthetic silica is contained as an anti-solidification agent capable of softening abrasive grain precipitates of the polishing material when the abrasive grains of the polishing material are dispersed into a dispersion medium, and sodium hexametaphosphate or pyrophosphate is contained as a dispersant capable of dispersing the abrasive grains of the polishing material into the dispersion medium.

Abstract: This invention aims to provide a method of manufacturing a cerium-based abrasive containing coarse particles in lower concentration and having higher polishing ability and excellent cleanability for a polished face. Further, the present invention provides a method of manufacturing a cerium-based abrasive, including the steps of pulverizing a raw material, roasting a raw material after pulverization and disintegrating a raw material after roasting, in which a cerium-based rare earth carbonate or a mixture of a cerium-based rare earth carbonate and a cerium-based rare earth oxide is used as a cerium-based abrasive raw material, and the step of pulverizing a raw material pulverizes a raw material through heating while the material is kept immersed in aqueous solution.

Abstract: Disclosed herein is a method for producing potassium fluoroniobate crystals by which highly pure, large-sized potassium fluoroniobate crystals can be obtained in high yield and which is advantageous from the viewpoints of material cost and material-dissolving operation; and potassium fluoroniobate crystals. This production method comprises the first and second steps (a) and (b) of (a) adding a potassium-containing electrolyte to a starting material comprising niobium to precipitate potassium oxyfluoroniobate and/or fluoroniobate as coarse crystals, and separating the coarse crystals by filtration, and (b) dissolving the coarse crystals in a recrystallization solvent that is an aqueous solution comprising 12 to 35% by weight of hydrofluoric acid and that has been heated to a temperature of 50° C. or more, and cooling the solution to 40° C. or lower at a cooling rate of less than 20° C./h to precipitate potassium fluoroniobate as crystals.

Abstract: This invention is a method for producing a cerium-based abrasive which includes: a step of grinding raw material for the cerium-based abrasive; a step of roasting the ground raw material; and a step of subjecting the roasted raw material to wet processing, the method being characterized in that it further includes a lower-temperature re-roasting step of heating the wet-processed raw material at 200 to 700° C. In the invention disclosed in this application, an abrasive with particularly preferable properties can be produced by fully drying the wet-processed raw material in a drying step, and subsequently subjecting the dried raw material to the lower-temperature re-roasting step.

Abstract: The present invention provides a method of examining quality of cerium-based abrasives which can simply determine their grinding characteristics. Specifically, the method employs X-ray diffractometry to examine qualities based on, for example, B/A wherein A and B are peak intensities relevant to LnxOy and LnF3, respectively. The present invention further provides: a method of producing a cerium-based abrasive which can give cerium-based abrasive with specific grinding characteristics; and a cerium-based abrasive which has specific grinding characteristics for specific purposes.

Abstract: Disclosed herein is a method for producing potassium fluorotantalate crystals, comprising heating, to 60° C. or higher, a starting solution prepared by adding hydrofluoric acid and hydrochloric acid, and, if necessary, water to a highly pure tantalum solution, adding potassium chloride to this starting solution, and cooling the mixture to 40° C. or lower at a cooling rate of less than 15° C./h to precipitate potassium fluorotantalate crystals, wherein the concentration of the hydrofluoric acid in the starting solution is not more than 20% by weight. By this method, highly pure, large-sized potassium fluorotantalate crystals can successfully be obtained in high yield. Moreover, disadvantages to equipment and operation in the prior art can be overcome to a significant extent with this method.

Abstract: A cerium-based abrasive and a production method of the cerium-based abrasive excellent in polishing properties of a high polishing speed and scarce formation of polishing scratches are provided by keeping the color of the abrasive in specified ranges or stably making fluorine be contained in the abrasive. For example, as such a cerium-based abrasive, examples include a cerium-based abrasive containing cerium oxide as a main component and having an L* value in a range not lower than 65 and or lower 90, an a* value in a range 0 or higher but 15 or lower, and a b* value in a range 10 or higher but 30 or lower in the case the color is expressed by an L*a*b* color system.

Abstract: The object of the present invention is to provide a method of producing low oxygen-containing potassium fluorotantalate crystals or low oxygen-containing potassium fluoroniobate crystals, the crystals obtained by the production method, and a method of analyzing oxygen contained in these crystals.

Abstract: The present invention provides a cerium-based abrasive slurry particles including a cerium-based abrasive particle of no less than 95% by weight of total rare earth oxides (TREO), in which the cerium-based abrasive particle has less than 3% by weight of fluorine content of TREO, and a particle size distribution determined by a laser diffraction method is within a predetermined range. And adhesion property is further improved by setting this fluorine content in 0.005 to 0.5% by weight of TREO.

Abstract: Regarding a cerium oxide-based abrasive containing cerium oxide as a main component and abrasive particles with an average particle diameter of 0.2 to 3.0 &mgr;m, the present invention provides a cerium-based abrasive containing coarse particles of 10 &mgr;m or larger in a concentration of 1000 ppm or lower (by weight) or magnetic particles in a concentration of 1000 ppm or lower (by weight). The coarse particles or the magnetic particles are particularly preferable to exist in a concentration of 300 ppm or lower (by weight). Further, by controlling an average value of the specific surface area of the abrasive particles to be within 0.5 to 30 m2/g, the resulting abrasive is provided with a high cutting property and is capable of forming a polished face with high precision. The production method of such cerium-based abrasives comprises control being the concentration of the coarse particles and the classification point and repeated classification.

Abstract: A polishing material is provided in which the dispersibility of the abrasive grains of the polishing material having, as a major component, rare earth oxides including cerium oxide is made better and the hardness of abrasive grain precipitates is reduced, and at the same time high efficiency of polishing can be achieved stably. According to the present invention, in a polishing material having, as the major component, rare earth oxides including cerium oxide, any one of crystalline cellulose, calcium secondary phosphate, a condensate of sodium &bgr;-naphthalenesulphonate and formalin, and synthetic silica is contained as an anti-solidification agent capable of softening abrasive grain precipitates of the polishing material when the abrasive grains of the polishing material are dispersed into a dispersion medium, and sodium hexametaphosphate or pyrophosphate is contained as a dispersant capable of dispersing the abrasive grains of the polishing material into the dispersion medium.

Abstract: The present invention provides a method of examining quality of cerium-based abrasives which can simply determine their grinding characteristics. Specifically, the method employs X-ray diffractometry to examine qualities based on, for example, B/A wherein A and B are peak intensities relevant to LnxOy and LnF3, respectively. The present invention further provides: a method of producing a cerium-based abrasive which can give cerium-based abrasive with specific grinding characteristics; and a cerium-based abrasive which has specific grinding characteristics for specific purposes.

Abstract: There is provided a cerium-based abrasive which enables formation of a highly accurate polished surface and has improved grindability. There is also provided a method of evaluating cerium-based abrasives in a relatively easy manner. In order to achieve the above objects, the cerium-based abrasive of this invention is a cerium-based abrasive containing 40% by weight or more of cerium oxide (on the basis of the total weight of rare earth oxides) which is characterized by further containing 0.5 to 10% by weight of fluorine per 100% by weight of the cerium-based abrasive, in terms of atomic weight, and polishing particles consisting of crystals with a lattice constant measured by an X-ray powder diffraction method ranging from 0.544 to 0.560 nm.

Abstract: The present invention provides a stock material for cerium-based abrasives which can be sintered at a relatively low roasting temperature without causing abnormal growth of the particles. More concretely, the stock material for cerium-based abrasives is produced by calcinating the carbonate of rare earth at a given temperature level to partly convert it into the oxide of rare earth in such a way to produce the mixed stock material having a loss on ignition of 0.5 to 25% on a dry basis, determined by heating at 1000° C. for 1 hour.

Abstract: Disclosed herein is a method for producing potassium fluorotantalate crystals, comprising heating, to 60° C. or higher, a starting solution prepared by adding hydrofluoric acid and hydrochloric acid, and, if necessary, water to a highly pure tantalum solution, adding potassium chloride to this starting solution, and cooling the mixture to 40° C. or lower at a cooling rate of less than 15° C./h to precipitate potassium fluorotantalate crystals, wherein the concentration of the hydrofluoric acid in the starting solution is not more than 20% by weight. By this method, highly pure, large-sized potassium fluorotantalate crystals can successfully be obtained in high yield. Moreover, disadvantages to equipment and operation in the prior art can be overcome to a significant extent with this method.